Exploring Atomic-Scale Interactions at the Interface of Reducible Oxide and Ruthenium Nanocatalyst for Ammonia Decomposition

Restructuring atomic-scale interfaces between noble metal nanoparticles and metal oxides provides a promising approach to enhancing catalytic properties. In this study, Ru nanoparticles were supported on CeO₂, ZrO₂, and HfO₂ via pyrolysis of MOFs under oxygen-suppressed high-temperature conditions. Despite its nearly ideal particle size (∼2.3 nm), the Ru-CeO₂/C catalyst exhibited the lowest ammonia decomposition activity. X-ray absorption spectroscopy and DFT calculations revealed that electron transfer from Ru to CeO₂ formed positively charged Ru and partially reduced Ce⁴⁺, weakening the catalytic performance. In contrast, oxygen-deficient ZrO₂ and HfO₂ support donated electrons to Ru, preserving its metallic state. These findings demonstrate that the reducibility of oxide supports governs the direction and magnitude of interfacial charge transfer, directly tuning catalytic behavior. This study provides insights into the design of oxide-supported Ru catalysts for ammonia decomposition.